2D upper bound analysis of ECAE through 2θ-dies for a range of channel angles

Abstract

Equal Channel Angular Extrusion (ECAE), sometimes referred to as Equal Channel Angular Pressing (ECAP), is a Severe Plastic Deformation technique. However the energy-power parameters of ECAE have not been fully addressed in previous known publications. The present article is focused on the punching pressure, accumulated plastic strain, and dead metal zone geometry estimation during ECAE of metal workpieces through a 2θ-die with a channel intersection angle of 2θ>0° and 2θ≠90°. Computational analytical results for ECAE technological parameters have been analytically derived for planar flow of a plastic, incompressible, non-hardening metal workpiece in an angular Segal die with 2θ>0° and 2θ≠90°. This is accomplished through the use of an Upper Bound Method (UBM) with Discontinuous Velocity Field (DVF) introduction. The development of the Dead Zone (DZ) for metal ECAE through a 2θ-die with 2θ>0° and 2θ≠90° has been analytically investigated. The obtained computational results for 2θ-die have been compared with the slip line analytic solutions of Segal for non-rectangular 2θ-dies of the same geometry. Good agreement between the two computational results has been found. The physical modeling techniques using plasticine have confirmed the appearance of a dead zone and material flow dynamics during ECAE through the Segal 2θ-die.

ECAP process improvement based on the design of rational inclined punch shapes for the acute-angled Segal 2θ-dies: CFD 2-D description of dead zone reduction

“…For the last 20 years a number of research efforts in materials science related fields have been focused on wider development, implementation, commercialization and improvement of new material forming methods known as Severe Plastic Deformation (SPD) schemes (Boulahia et al, 2009;Haghighi et al, 2012;Han et al, 2008;Laptev et al, 2014;Minakowski, 2014;Nagasekhar et al, 2006;Nejadseyfi et al, 2015;Perig et al, 2013aPerig et al, , b, 2015Perig and Laptev, 2014;Perig, 2014;Rejaeian and Aghaie-Khafri, 2014). The classical SPD processing method is Segal's Equal Channel Angular Extrusion (ECAE) or Equal Channel Angular Pressing (ECAP) material forming technique (Segal, 2004).…”

Two-parameter Rigid Block Approach to Upper Bound Analysis of Equal Channel Angular Extrusion Through a Segal 2θ-die

“…The obtained results (2)- (11), derived with two-parameter UBM introduction (○○○) have been compared with upper bound solution by Perig 22 (▬▬) for relative punching pressure (p/2k) Perig and summary shear γ Perig 22 for 2θ=75° (Figures 8a,b), 2θ=105° (Figures 8c,d), 2θ=120° (Figures 9a,b), and 2θ=135° (Figures 9c,d): …”

“…Tóth et al 28 have proposed a novel analytic approach to ECAE copper flow with the introduction of a flow line model. Milind 4,5 , Faraji et al 6 , Laptev et al 7 , Luri et al 8 , Luri & Luis 9 , Medeiros et al 10 , Narooei & Karimi Taheri [12][13][14] , Paydar et al 15 , Perig & Laptev 19 , Perig 22 , Reihanian et al 24 , Talebanpour & Ebrahimi 27 and others. Altan et al 3 have addressed the Upper Bound Method (UBM) with continuous trial velocity fields for description of metal ECAE motion through the Segal die.…”

“…Simple physical simulation experiments for analysis of ECAE flow through a non-rectangular Segal 2θ-die in Figures 3-6 show the complex structure of the dead metal zone CEDF (Figures 3-6), which has not been adequately addressed in previous known publications [1][2][3][4][5][6][7][8][9][10][12][13][14][15]19,22,24,27,28 . Moreover, the two-parameter rigid block approach to the two-parameter UBM of metal flow during ECAE with trial Discontinuous Velocity Field (DVF) introduction and accounting for the complex geometry of dead zone CEDF (Figures 3-6) for metal flow through a Segal 2θ-die has not been addressed in proper way in previous known publications [1][2][3][4][5][6][7][8][9][10][12][13][14][15]19,22,24,27 .…”

“…Moreover, the two-parameter rigid block approach to the two-parameter UBM of metal flow during ECAE with trial Discontinuous Velocity Field (DVF) introduction and accounting for the complex geometry of dead zone CEDF (Figures 3-6) for metal flow through a Segal 2θ-die has not been addressed in proper way in previous known publications [1][2][3][4][5][6][7][8][9][10][12][13][14][15]19,22,24,27 . All previous research [1][2][3][4][5][6][7][8][9][10][12][13][14][15]19,22,24,27 has not fully addressed the complex geometry of the dead metal zone CEDF (Figures 3-6) nor the influence of complex dead zone geometry CEDF (Figures 3-6) on the character of metal flow during workpiece ECAE through a Segal 2θ-die applying a two-parameter UBM in the form of a two-parameter RBM with trial DVF. This insufficient analysis of energy-power parameters during ECAE with an introduction of the two-parameter UBM with DVF was the stimulus, which resulted in the research reported in the present article.…”